In today's global political climate the security of drummed products is coming under ever closer scrutiny. It has long been the practice to apply overseals of one kind or another with special hand and power tools which were able to crimp a metal portion of the overseal tightly around an upstanding opening neck designed to receive the seal. Moreover, the application step itself is quite labour intensive and relatively inefficient. Consequently a number of hand applied overseals or caps have come forth which to a certain degree obviate the above-mentioned application tools. These hand-applied overseals are for the most part easily snapped onto the container opening neck and usually almost as easily snapped off. While these plastic snap-on caps or overseals serve to dress up a container such as a 55 gallon (275 litre) drum, giving the closure area a finished appearance and some added degree of cleanliness, there is still much to be desired in terms of drum security. To be effective such drum closure caps or overseals need to meet a number of rather demanding criteria. Obviously the hand application has to be simple and relatively effortless to satisfy normal filling line speeds. Once the drum is shipped, of paramount importance is the ability of the cap or overseal to guard against unauthorized access to the drum contents. This means that the cap or overseal cannot be physically removed without destroying same or making such unauthorized access clearly noticeable and such that the cap or overseal cannot be reapplied in unaltered form to the drum closure. In this regard, plastic, manually-applied caps or overseals currently in general use for both steel and plastic drums are, for the most part, easily pried off in an undetected manner particularly when in a warmed state. In other words “easy-on easy-off”.
A performance criterion also of major importance is the ease with which the cap or overseal can be removed from the underlying drum closure in an authorised manner such that subsequent replacement of the overseal is not possible. Normally this requires destruction of the cap or overseal in some fashion to prevent reuse. In this regard the use of sharp cutting or puncturing implements is undesirable due to the likelihood of injury or of accidental damage to the underlying closure. Thus, in addition to the overseal's robust construction, hand removability is yet another advantageous attribute.